Calls to the police reporting men’s assaults on their wives or intimate partners rose 10 percent in areas where the local National Football League team lost a game they were favored to win, according to an analysis of 900 regular-season NFL games reports researchers in a paper in the Quarterly Journal of Economics.

Football games are emotionally laden events of widespread interest, typically garnering 25 percent or more of a local television viewing audience. The disappointment of an unexpected loss, the researchers concluded, raises the risk that football fans may react inappropriately.

In contrast, co-authors David Card of the University of California, Berkeley and Gordon Dahl of the University of California, San Diego found no decrease in reports of violence following an unexpected win by the local team or by the team’s loss in a game that was expected to be close.

“Our paper points to the important role expectations play in modulating our emotions,” said Dahl, associate professor of economics at UC San Diego. “Losing only provokes violence if the loss was unexpected.”

“Our results suggest that the overall rise in violence between the intimate partners we studied is driven entirely by losses in games that matter most to fans,” Card said. The timing of the calls to police also indicated that violence occurred within a narrow window roughly corresponding to the final hour of a game and the two hours after.

Card and Dahl say their findings confirm earlier work suggesting that unexpected disappointments affect us more strongly than pleasant surprises. “This is not limited to football,” Card said. “Someone who gets a speeding ticket on the way home, for example, might also be more likely to act out in a way he would later regret.”

Card and Dahl compared the pre-game betting odds to the game results of regular-season games for six NFL teams – the Carolina Panthers, Detroit Lions, New England Patriots, Denver Broncos, Kansas City Chiefs and Tennessee Titans – between 1995 and 2006. This information was matched to records collected from 763 jurisdictions in the relevant states from the National Incident-Based Reporting System (NIBRS), a database of local police reports.

In one-third of the games they tracked, the local team was expected to win by four or more points. When the favored team lost, however, Card and Dahl’s analysis revealed a spike in reports of violence by men against a female partner at home, as compared to weeks the home team did not have a game.

This pattern was most pronounced for losses the authors judged to be more emotionally charged. For example, the rise in police reports after upset losses to a traditional rival (20 percent) was about twice that after upset losses to a non-rival team (8 percent). Violence was also more likely to increase when the local team was still in playoff contention or had a particularly frustrating performance—suffering four or more sacks or turnovers or losing 80 or more yards to penalties. An analysis of the combined effect of these factors showed a 17 percent increase in reports of violence after an upset loss to a rival team while the local team was still in playoff contention.

Violence did not rise appreciably after upset losses when these criteria did not apply, for example, when the local team was no longer in playoff contention, the opponent was not a rival, or the local team’s performance was not especially egregious.

The research was funded by the Demographic and Behavioral Sciences Branch of the NIH’s NICHD, the National Institute of Child Health and Human Development.